Valve mechanism



Oct. 11, 41949. H. A. MEINECKE VALVE MECHANISM 4 Sheets-Sheet 1 Filed March 2, 1945 INVENTOR.

Oct. 11, 1949. AMENECKE 2,484,109

VALVE MECHANISM Filed larch 2, v 1945 4 Sheets-Sheet 3 AVERR 65 HIGH SPEED TIMING IN V EN TOR.

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Oct. 11, 1949. H. A. MEINECKE 2,484,109

VALVE MECHANISM Filed March 2, 1945 4 Sheets- Sheet 4 IN VEN TOR.

Patented Oct. 11, 1949 UNITED STATES PATENT OFFICE 18 Claims.

This invention relates to valve mechanism for internal combustion engines and more particularly to hydraulic tappet mechanism for operating the exhaust and intake valves of such engines, an important object of the invention being to provide an improved hydraulic tappet of the self-adjusting or compensating type constructed and operable in improved manner to automatically vary the performance characteristics of the engine.

Heretofore, hydraulic tappets in commercial use have been employed in the operation of exhaust and intake valves for the purpose of eliminating tappet adjustment as well as providing automatic compensation or take-up for play or looseness between the tappet body and cam shaft consequent to clearance necessary for valve stem expansion, which in the case of conventional mechanical tappets frequently results in noisy operation of the valves. A conventional compensating tappet of the hydraulic type usually comprises a tubular tappet body having in the upper end thereof a plunger contacting the valve stem withthe space in the tappet body below the plunger divided into two hydraulic chambers, the lower of which acting at all times as the reservoir for the other. A one way check valve is generally interposed between the chambers to prevent the oil or hydraulic medium from returning to the reservoir chamber, the construction being such that oil is trapped in the upper chamber during operation and provides an incompressible hydraulic column through which the thrust of the cam is positively transmitted to the valve without any appreciable lost motion, thus ensuring a constant and predetermined timing of the valve and a fixed opening and closing operation thereof.

One of the aims of the present invention is to provide a hydraulic tappet mechanism which will not only possess any or all of the advantages of the conventional self-adjusting or compensating tappet but additional important advantages in.

the improvement of the performance of the engine and in permitting efiicient operation over a wider power and speed range. It is well known that an engine designed with high speed timing and large valve areas to given an early opening and late closing of the valve, as well as a relatively wide or large opening thereof, will produce up to at least one third more maximum power, but an engine so timed will either not run or'will operate very inefficiently at low speeds. Conversely, an engine designed with low speed timing and small valve areas will operate advantageously at low speeds but will not give eflicient performance at high speeds. In view of these limitations it is customary to provide valve sizes and timing which are a compromise between the two extremes, yet whether such engines are equipped with ordinary mechanical tappets or conventional hydraulic compensating tappets the operation and performance characteristics are not satisfactory at the low and high speed limits of the particular engine, and furthermore the maximum power available in the engine is not utilized.

It is an object of the invention to overcome these disadvantages and to provide an engine having an improved hydraulic mechanism operable to vary the size of valve opening and the timing thereof in accordance with the engine speed so as to enable the engine to perform efficiently throughout the range from low to high speed while at the same time increasing the power output thereof.

A further object of the invention is to provide an engine in which the effective maximum opening of the valve, the timing thereof and the cam design are such as are suitable for high speed operation and maximum power output, these characteristics being obtained at high speed operation by transmitting the cam thrust to the valv without appreciable lost motion. However,

the construction is such that as the speed is reduced a progressively increasing lost motion or telescoping action is introduced in the tappet mechanism between the cam and the valve altering the valve timing and reducing the lift or effective opening of the valve so as to maintain eficient operation. The compensating action is progressive between maximum high and low speeds and at the latter limit the lost motion or telescoping action of the tappet mechanism is greatest, thus affording the proper timing and valve opening needed to enable the engine to perform properly at the low speed limit.

A further object of the invention is to provide a self-adjusting or compensating hydraulic tappet mechanism wherein means is provided for maintaining and ensuring eflicient and uniform operation irrespective of changes in viscosity of the oil or other lubricating medium occasioned by variations in the temperature thereof.

Still another object of the invention is to provide a hydraulic tappet device having a chamber interposed between telescoping parts of the tappet through which oil is circulated during operation, means being provided for controlling the oil circulation in accordance with the operating slidable in the guides 2|.

Speed of the engine to vary the telescoping action of the tappet parts, and means in addition being provided for progressively varying the ef-' fective circulatory passage for the oil so as to compensate for variations in the viscosity of the oil due to changing oil temperatures.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Fig. 1 is a fragmentary side elevation illustrating a portion of an internal combustion engine embodying the present invention. t

Fig. 2 is an enlarged section taken substantially through lines 22 of Fig. 1 looking in the direction of the arrows.

Fig. 3 is a vertical section taken substantially through lines 3-3 of Fig. 1 looking in the direction of the arrows.

Fig. 4 is an enlarged fragmentary sectional view, in part similar to Fig. 2, illustrating an adjusted position of the thermally responsive control valve.

Fig. 5 is a view somewhat similar to Fig. 4 illustrating a modification of the thermally responsive control valve.

Fig. 6 is a graph illustrating typical examples of valve opening for one cycle of engine operation utilizing high speed and average speed timing obtainable by virtue of the present invention.

Figs. 7, 8 and 9 illustrate diagrammatically the time of opening and closing of the intake and exhaust ports during one cycle of engine operation in which low speed, high speed and average speed time, shown respectivelyin these views, are obtained by virtue of this invention.

Fig. 10 is a fragmentary sectional view, in part similar to Fig. 2, illustrating a further embodiment of the invention.

Fig. 11 is aview in part similar to Fig. 2 illustrating another embodiment of the invention.

Fig. 12 is a view similar to Fig. 11 illustrating a further embodiment;

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

In the drawings several embodiments of the invention are illustrated as applied to an internal combustion engine of the multi-cylinder type comprising a cylinder block 2|] bored at spaced intervals to receive a number of valve stem sleeves or bushings 2|. The exhaust and intake valves 22 of the engine are of the poppet or mushroom type having depending valve stems 23 Surrounding the lower portions of the valve stems are compression springs 24 held in place at their lower ends by spring retainers 25, these springs normally urging the valves against their seats in accordance with conventional practice.

Referring to the embodiment of the invention illustrated in Figs. 1 to 4 inclusive, the lower portion a of the cylinder block below the valve springs is formed with a number of vertically extending bores in line with the valve stems and adapted to'slidingly receive a like number of tubular tappet bodies 26 each terminating in a fiat head 26a engageable by a cam lobe 21 secured to the cam shaft 28 of the engine. Inasmuch as each of the valves 22 is controlled and operated in the same manner in accordance with the present invention, a description of the mechanism for accomplishing this purpose applicable to one valve will suflice.

, The tappet body 26 is formed with a cylindrical chamber 29 and within the upper end of this chamber is fitted the cylindrical head 30a of a plunger 30 engageable with the lower end of the valve stem 23. The head 30a of the plunger has a close sliding fit within the chamber 29 such as to prevent any appreciable leakage of oil past the plunger during operation of the tappet body. The plunger 30 has 9. depending stem 3| -fixed thereto and extending centrally through the chamber 29 and terminating at its lower end at a point spaced from the bottom of the chamber. Surrounding the stem 3| is a relatively light compression spring 32 held in position between the plunger and the bottom of the chamber '29.

The tappet body 26 is machined to provide a lower annular groove 33 communicating with the chamber 29 through the medium of a number of ports or holes 34. In constant communication with the oil groove 33 is an inlet oil duct formed in the boss 20a of the cylinder block, this oil duct leading from a main oil inlet conduit 31 extending longitudinally in the cylinder block and connected to a source of lubricating oil such as the oil sump forming part of the lubrication system of the engine. There is preferably mounted within the oil passage 31 or 35 a conventional spring pressed one-way check valve, similar for exampie, to the construction of Fig. 10 or Figs. 11 and 12, which normally is held open by the oil pressure to allow oil to flow through the passages into the groove 33 and thence through ports 34 into the interior of the tappet body. This check valve will close when the cam raises the tappet body thus tending to force oil out of the chamber 29 through passage 35. The check valve will also close when the flow of oilceases, such as when the engine is not running, in order to prevent oil draining out'of the tappet body. The conduit 31 is in communication with a number of oil ducts 35 which supply oil under pressure to the various tappet bodies 25 ofthe engine.

The tappet body 26 is machined to provide an upper annular oil groove 38 similar to the groove 33 and spaced a suitable distance thereabove. The groove 38 communicates with the chamber 29 in the tappet body through the medium of a number of ports or holes 39 and is also in constant communication with an outlet oil duct 40 formed in the portion 20a of the cylinder block. The oil duct 40 is formed intermediate its ends with an enlarged cylindrical recess within which is mounted a rotatable valve 4| having a passage 4| a therethrough connecting the ends of the oil duct 40 and through which oil may flow into a sump or trough 42. Excess oil overflowing from this trough will spill through the opening 43 and return to the crankcase of the engine.

The cylindrical valve 4| extends longitudinal] through the portion 20a of the cylinder block and is provided with a duct'or passage 4| a for each of the tappet bodies of the engine. Secured to one end of the valve 4|, as shown in Figs. 1 and 3, is a crank arm 44 pivotally connected at its flows from trough 42. A drain hole 49 is provided in the bottom of chamber 48.

By virtue of this construction it will be seen that the thermostat 41, which may be of any conventional type, is responsive to the temperature of the lubricating oil in the engine crankcase. Hence, expansion and contraction of the thermostat, consequent to variations in the oil temperature, will shift the plunger 46 vertically, thus turning the crank arm 44 and partially rotating the valve 4|, such as from the position shown in Fig. 2 to that shown in Fig. 4, or

vice versa. Thus, it will be seen that rotation of the valve 4| out of its fullyopen position shown in Fig. 2 will progressively restrict the passage of oil through the duct 4|] from the chamber 29 into the sump or trough 42' The construction is such that the valve 4| will be in its fully open position, shown in Fig. 2, when the lubricating oil in the engine lubrication system is at its lowest operating temperature, such as at the time of starting the engine, and when the viscosity of the oil is greatest. Since the thermostat 41 is exposed to the oil within the chamber 48, the temperature of which corresponds substantially to the temperature of the oil in the lubricating system, the thermostat will expand progressively as the temperature of the oil rises and the viscosity thereof decreases. As a consequence, the valve 4| will progressively move toward closed position in proportion to the temperature of the oil and the decrease in viscosity thereof. The construction, however, is such that the valve at no time will fully close oii the duct 4!] connecting the chamber 29 in the tappet body with the sump or trough 42. By this construc-- be seen that the operating characteristics of the tappet mechanism will remain constant and the same operating characteristics will be maintained regardless of the temperature of the oil.

The embodiment illustrated in Fig. is in all respects substantially the same as the embodiment illustrated in Figs. 1 to 4 inclusive and above described with the exception that a different thermally responsive means is provided for controlling the effective outlet passage of oil from the tappet body in accordance with the temperature and viscosity of the oil. In Fig. 5 the upper annular groove 38 in the tappet body is in constant communication with an angularly extending passage 50 in the portion 20a of the cylinder block. The passage 50 leads into a longitudinally extending sump or trough 5| corresponding substantially to the trough 42 of the previous embodiment. Riveted to one wall of this trough is one end of a bi-metal heat responsive spring 53 which is provided at its free end with a semi-spherical valve 52 located opposite the upper end of the oil duct or passage 50. The bi-metal spring 53 is at all times submerged in the oil within the trough 5| and is responsive to the temperature of the oil therein. A rise in temperature of the oil produces an outward deflection or expansion of the spring thereby moving the valve 52 toward the end of the passage 50 and progressively restricting the outlet of this passage. The valve is prevented from fully closing ofi the passage by means of a projecting stop 54 engageable with the end of the spring. Thus, it will be seen that the valve 52 controlled by the bi-metallic spring 53, which is deflected in one direction or the other in accordance with the oil temperature within the sump or trough 5|, functions in the same manner as the thermostatically controlled valve 4| to vary the efiective passage connecting the tappet body with the trough in accordance with the temperature and viscosity of the oil.

In the embodimentillustrated in Fig. 10 the tappet body 26 is provided with a solid partition 26!) above the lower end thereof against which the spring 32 bottoms. By this construction the stem 3| of the plunger 30 and the return spring 32 for the tappet body are somewhat shorter than the corresponding construction illustrated in the previous embodiment. The head 26a of the tappet, which is engaged by the cam 21, is in this embodiment made as a separate part having a cylindrical extension press fitted into the lower end of the tappet body. Immediately above the bottom wall 26b of the chamber 29 the tappet body is drilled to provide a number of oil ducts or holes 55 which communicate with an annular oil groove 56 formed in the boss 20a of the cylinder block. This groove is in constant communication with a passage 51 within which is suitably mounted a one-way check valve 58 backed by a light spring. The check valve will close when the cam commences to raise the tappet body thus tending to force oil out of the tappet chamber. The passage 51 leads into the lower end of a sump or trough 59 extending longitudinally of the cylinder block. A pliable sealing ring 60 is mounted in the cylinder block in engagement with the tappet body for the purpose of preventing the reservoiror sump 59 from draining when the engine is idle. The tappet body is drilled to provide a number of upper ports or holes 6| which are in communication with an upper annular groove 62 similar to the groove 56 but spaced a suitable distance thereabove. Communicating with this oil groove is an oil outlet passage 63 plugged at its outer end but communicating through a top port 64 with a chamber 65 closed at its upper end by means of a removable cap 65a. The port 64 is controlled by means of a check valve 66 which is adapted to open under pressure of oil flowing out of the tappet body through the passage 63 into the chamber 65. A tapered port 61 eifects communication between the chamber 65 and the upper end of the reservoir or sump 59 and this port is controlled by means of a correspondingly tapered valve 68 carried by an expansible and contractible bi-metallic spring 69 secured to the wall of the reservoir. Oil from the engine lubrication system flows through a pipe 10 into the reservoir 59, which is open to the atmosphere, maintaining this reservoir filled at all times to overflowing. Oil flowing into the reservoir from the pipe 10 passes through a line wire mesh screen I! which acts as a bafile to prevent the passage of air or gaseous oil bubbles into the inlet passage 51 leading to the interior of the tappet body.

It will be understood that since the position of the valve 68 is controlled by the bi-metallic spring 69, which is deflected in one direction or ternal combustion engines on account of the fact that the effective .opening of the exhaust and intake valves and the time of opening and closing thereof have been fixed or constant. These characteristics have been governed by the size of valve and the contour of the cam selected for the particular engine. No appreciable variaeration at relatively low speeds will be limited .as to its upper speed range and, will not produce the power obtainable from an engine timed for high speed .operation. In Fig. 7 there is illustrated a typical low speed timing diagram in which the curve :1: represents the degrees of opening of the intake valve between the lines 3: and x", and the curve 3 represents the degrees of opening of the exhaust valve between lines 11 and y". The intake valve with this timing arrangement opens at a point 5 before top dead center and closes at a point 35 after bottom dead center. The exhaust valve opens 45 before bottom dead center and closes 5 after top dead center. A relatively small overlap of the valves occurs with this timing permitting low speed operation. Fig. 8, on the other hand, illustrates a typical timing diagram for a high speed engine having much higher maximum power output but incapable of operating efficiently at low speed. In this case the period of .opening of the intake valve is from line :2 to line 11:, the valve opening 43 before top dead center and closing 75 after bottom dead center. The period of opening of the exhaust valve is from 80 before bottom dead center to a point 32 after top dead center. The much greater overlap of the exhaust and intake valves in this case permits the desired high speed operation and an engine timed in this manner will produce at least one third more power than an engine timed according to the diagram .of Fig. 7 but will not function at low speeds.

Engines timed as in Figs. 7 and 8 are generally designed for special purposes. Hence, engines constructed for general purposes are given a compromise timing between these extremes such as indicated in the diagram of Fig. 9 which represents a typical average speed timing in which the intake valve opens at 10 before top dead center and closes at a point 40 after bottom dead center. The exhaust valve in this case opens at 50 before bottom dead center and closes at 10 after top dead center.

It is possible by virtue of the present invention to obtain the advantages of the timing shown in all of the diagrams of Figs. 7, 8 and 9, hence enabling the engine to operate efficiently at maximum low and high speeds and throughout the speed range therebetween. Accordingly, the exhaust and intake valve areas may be made large to give the maximum openings needed for maximum engine speed and the cams 21 designed so as to time the opening and closing of the valves and give the maximum lift to the valves at the top speed selected, such as the high speed perform-1 ance available with a timing diagram shown in Fig. 8. However, by introducing into the tappet mechanism in accordance with the present invention a telescoping action which varies in direct proportion to the engine speed it is possible to alter both the effective valve openings and the normally set timing shown, for example, in Fig. 8

and to progressively vary this timing as well as reduce the amount of effective opening of the 5 valves so that a low speed timing, such as illustrated in Fig. 7, or an average speed timing, such as illustrated in Fig. 9, will result at predetermined stages in the engine operation. In other words, by virtue of the telescoping action of the tappet mechanism the timing and effective opening of th valves will be automatically altered to give the timing and valve opening needed for most efficient operation at all speeds. The variation in valve lift and, hence, the effective opening of the valves based on the timing shown in Figs. 8 and 9 are graphically illustrated in Fig. 6. The curves A and B in this view are found by plotting successive points on the graph representing the lift or amount of opening of the valve, measured in inches, for each degree of angular motion of the cam shaft during a complete cycle of operation.

The telescoping action of the tappet mechanism to varythe timing and effective opening of the valves, as above described, will be readily understood by reference to the operation of the device shown in Fig. 2. With the parts positioned as shown oil will circulate through the chamber 29 in the tappet body 26, entering from inlet passage 35 through ports 34 and exhausting through ports 39 into outlet passage 40. As the tappet body 26 is lifted by the cam 21 the column of oil 29 will decrease in height so long as the passage 40 is,

uncovered by the oil groove 38 since oil during this time will be forced out of chamber 29 into the outlet passage 40. While this occurs the tappet body will telescope .on the plunger head 30a, moving upwards relatively to it without raising the valve. A lost motion between these parts is created delaying the time of commencement of the opening of the valve, and this latter will not occur until the outlet passage 40 is covered and an incompressible column of oil remains in the tappet body by the closing of the inlet and outlet passages leading thereinto. As soon as the oil grooves 33 and 38 move upwards out of communication with the passages and t0 the thrust of the cam will be transmitted through the colr umn of oil in the tappet body to the plunger head 30a, thereby raising the valve 22. The telescoping action of the tappet body and plunger 30a will compress the spring 32 and, hence, during closing movement of the valve the expansion of the spring will force the tappet body downwardly and ensure constant contact thereof with the cam. It will be apparent that the amount of oil forced or pumped out of the tappet body through groove 38 into outlet passage 40 during the initial rise of the tappet body under the thrust of the cam will depend upon the length of time that the outlet passage is in communication with the groove. Furthermore, it will be apparent that the extent of telescopic action or lost motion travel of the tappet body relatively to the plunger head 30a will depend upon the amount of oil forced out of the tappet body before the oil in chamber 29 becomes an incompressible column by having no outlet therefrom. Hence, at the slowest speed of the engine the telescopic action will be greatest, since the passage 40 remains uncovered for the longest interval of time. This results in a late opening of each valve, such as i1- lustrated in Fig. 7. Moreover, since the telescopic action is greatest at this speed the cam will lift the valve the least height thus providingthe minimum effective opening past the valve.

As the engine speed is gradually increased the passages and will remain uncovered for gradually shorter intervals of time, and, hence, the circulation of oil through the tappet chamber 29 will progressively decrease. This will be accompanied by a progressive increase in height of the solid column of oil in the chamber causing the cam to commence its lift of the valve at progressively earlier stages. In other words, as the reciprocation of the tappet body increases in rapidity, due to increasing speed of rotation of the cam shaft, less and less oil will circulate through the tappet chamber 29 and be forced out of the chamber into the outlet passage since the passages 35 and 40 will be uncovered by the grooves 33 and 38 for increasingly shorter intervals of time. As the height of the solid or incompressible column of oil in the tappet chamber increases, the height that the cam lifts the valve 22 will progressively and proportionately increase, and furthermore the timing of each valve will change giving an increasingly earlier opening and later closing thereof. the oil grooves 33 and 38 will reciprocate into and out of registry with the oil passages so rapidly that no appreciable amount of oil will enter or leave the tappet chamber and, hence, the oil column in the chamber will remain at substantially maximum height and provide substantially a positive connection between the tappet body and plunger 30. At this time there will be no appreciable telescopic action or lost motion between the tappet body and plunger and, hence, the valve operation will be substantially the same as if the tappet body and plunger were one piece. Under these conditions the maximum power output will be available with a high speed valve timing such as shown in Fig. 8 accompanied by maximum lift and effective opening of the valve as shown in Fig. 6.

The operation of the device shown in the embodiment of Fig. 10 is substantially the same as that above described in connection with the embodiment Of Fig. 2. Inthe construction of Fig. 10 the ports and GI in the tappet body 26 reciprocates during rotation of the cam shaft relatively to the oil grooves 56 and 62 which are in constant communication with the inlet and outlet pasages 51 and 63 respectively. Thus, reciprocation of the tapped body under the action of the cam 21 will result in making and breaking communication between the ports 55 and 6| leading from the tappet chamber 29 and the inlet and outlet grooves 56 and 62. Hence, as in the previous embodiment, the amount of oil circulating through the tappet chamber 29 will be governed by the interval of time that this chamber is in communication with the inlet and outlet passages during each reciprocating cycle. Accordingly, as the speed of the engine and the speed of rotation of the cam shaft progressively increase, the height of the incompressible column of oil in the chamber 29 will progressively and proportionately increase, thereby resulting in proportionately increasing the height that the cam lifts the valve 22. At the same time the valve will be given an increasingly earlier opening and later closing.

In each of the embodiments shown in Figs. 2 and 10 it will be noted that the stem 3| depending from the plunger 30 terminates at its lower end at a predetermined distance from the bottom wall of the tappet chamber 29. During normal operation the telescoping action of the tapp t At or near the top speed of the engine body 26 with respect to the plunger head 30a will not be sufiicient to cause the bottom of the tappet chamber to engage the lower end of the stem 3|. However, in the event the oil supply fails the tappet body will rise sufficiently under the thrust action of the cam to cause the bottom of the tappet chamber to engage the lower end of the stem 3| and thereby lift the valve 22. The stem 3| thus performs two functions, namely, as a guide for the light spring 32 and also a safety means for ensuring operation of the valve in the event of failure of the oil supply.

In the embodiment of the invention illustrated in Fig. 11 the construction in many respects is similar to the embodiment of Fig. 2 differing therefrom primarily in the provision of inertia means for assisting in varying the effective circulatory flow of oil or other liquid medium into and out of the chamber 29 during the reciprocation of the tappet body. In this embodiment also there is interposed in the inlet passage 35 a spring pressed one-way check valve 58 similar to hat illustrated in Fig. 10. In Fig. 11 the outlet passage 40 has an upper angular extension 40a terminating in a, valve seat engaged by a tapered valve 15a carried by a weight or inertia member 15 mounted within a chamber 16. The inertia member 15 is guided for vertical movement by a downwardly projecting guide stem 11 secured to a. closure disk 18 for the chamber 16. The stem is slidable freely in a guide hole 19 in the member 15 and the chamber 16 at its lower end is provided with an outlet port or duct for the flow of oil from the chamber into a sump or trough 14 which may be supplied with oil from the lubricating system of the engine in the same manner as shown and described in connection with the embodiment of Fig. 10.

In the operation of the device shown in Fig. 11, as the cam 21 forces the tappet body 26 outwardly in a valve opening direction oil will be forced or pumped out of the chamber 29 through the passage 40 and at the same time the check valve 58 in the inlet passage 35 will close. Thus, oil is discharged from the chamber as the tappet body moves outwardly from the position of Fig. 11 in which the passages 35 and 40 are fully uncovered. This flow of oil progressively diminishes in volume until interruption thereof occurs when the oil grooves 33 and 38 move out of registry with these passages. As in the previous embodiments the volumetric discharge of oil from the tappet chamber during the outward movement of the tappet body will depend upon the speed of reciprocation of the tappet body.

The weight of the inertia member 15 is so selected that normally the pressure of oil discharged through the outlet passage 40 will lift the inertia member and permit oil to flow past the valve 40a into the chamber 16 and thence through port 80 into the trough 14. At the slowest speed of the cam shaft the interval of time in which the passage 40 is uncovered will be sufficient to overcome the inertia of the member 15 and lift the valve 150. off its seat a sufiicient distance to permit a free flow of oil out of the passage 40. As this interval of time is reduced by acceleration of the engine the wei ht 15 will be displaced upwardly from its seat to a less and less extent owing to the reduction in the time interval necessary to overcome its inertia. Hence, during this accelerating period less and less oil will be permitted to flow out of the chamber 29 past the valve 150. and, consequently, the height of the incompressible column of oil in the chamber 29 pulses thereof are so close together or so rapid, j that not sufilcient intervals of time will be availsubstantially a solid column of oil between the tion of the tappet body 26 and the pumping imable to overcome the inertia of the member 15 i and, hence, the circulatory flow of oil through the tappet body will substantially cease, producing 15 bottom of the tappet chamber and the plunger 30 and a substantially positive connection between the tappet body and plunger. Under such conditions these members will operate in unison without appreciable lost motion or telescopic ac.- tion therebetween. The inertia member 15 may be advantageously incorporated in any of the embodiments of the present invention. As a result 1 of its use, for example, no high degree of accuracy is needed in forming the ports in the tappet body and greater tolerances are permitted in determining the relative sizes, dimensions and spacing of 1 the ports and oil passages.

The embodiment illustrated in Fig. 12 corresponds in many respects tothat shown in Fig. 11 differing therefrom principally in the substitution of a spring pressed check valve in place of the inertia member 15. In Fig. 12 the outlet vpassage 8|, corresponding to the passage 40 in the previous embodiment, leads into a chamber 32 formed in a rib member which extends across or bridges the trough 83 which is supplied with oil from the lubrication .system in the manner shown in Fig. 10. The inner end of the passage 8| provides a seat for a check valve 84 which is pressed against the seat by means of a compression spring 85 interposed between the valve and a closure disk 86. Oil entering the chamber 82 through the passage 8| flows into the trough 83 through an outlet duct or port 81.

The operation of this embodiment is similar to that shown and described in connection with Fig. 11, the spring 85 being so selected as to weight or strength so as to cause the check valve 1 84 to resist flow of oil from the tappet chamber .50 through outlet passage 8| into the chamber 82 and thence into the trough. As in the case of the inertia member 15, the check valve 84 will only open when sufficient interval of time is permitted enable the pressure of oil in the outlet passage 8| to overcome the inertia of the spring 85. 1 When the pumping impulses of the tappet body 1 are so rapid that not suflicient interval of time the discharge of oil from the chamber through the outlet passage, resulting in the tappet body telescoping a predetermined amount on the plunger 30. During this action the spring 32, interposed between the plunger and tappet body, will be compressed. When the resistance to the discharge of oil from the chamber during outward movement of the tappet body attains a magnitude suflicient to overcome the resistance of the main valve spring 24, then the valve 22 will immediately commence to rise from its seat..

After the high point of the cam has passed beyond the end of the tappet body the main valve spring 24 will force the valve 22 into closed position with the tappet body and plunger 30 in telescoped relation. The spring 32 will then ex pand forcing the tappet body downwardly or inwardly to maintain its contact with the cam and at the same time forcing the plunger outwardly to maintain its contact with the end of the valve stem 23. This action, resulting in a telescopic movement of the tappet body and plunger away from each other, will increase the volume of the tappet chamber 29 and, hence, cause oil to be drawn into the tappet chamber through the inlet passage past the check valve therein. The check valve will close as soon as the expansion of the tappet chamber is completed or as soon as the cam commences to lift the tappet body in a succeeding valve opening operation.

I claim:

1. A cam actuated mechanism for actuating an engine valve, comprising a fixed body, a pair of coacting members arranged within said body in telescoping relation, one of said members having a chamber adapted to contain a body of fluid through which the thrust of the cam is transmitted to the other member for shifting the valve to open position, and inlet and outlet conduit means in said body adapted to communicate with ports in said chambered member for circulating a fluid medium through said chamber in one position of said chambered member to permit relative telescoping movement of the members and for substantially interrupting said circulation in another position of said chambered member to provide a substantially positive hydraulic connection between the members.

2. A cam actuated mechanism for actuating an engine valve, comprising a fixed body, a pair of coacting members arranged within said body in telescoping relation, one of said members having a chamber adapted to contain a body of fluid through which the thrust of the cam is 1 during the reciprocation f the tappet body to transmitted to the other member for shifting the valve to open position, and means including spaced ports in said body opening into said chambered member for introducing a fluid medium into said chamber and discharging it therei permitted t overcome the inertia of the from in one position of said chambered member tappet body will be created. The amount of this flow will, of course, be governed by the speed 1 of reciprocation of the tappet and-will progressively decrease as this speed increases.

When the tappet body is raised by the cam a contraction of the tappet chamber will occur owing to to permit relative telescoping movement of the members and for restricting said introduction of fluid means in another position of said chambered member to provide a substantially positive hydraulic connection between the members.

3. A cam actuated mechanism for actuating an engine valve, comprising a supporting body, a pair of coacting members arranged in said body in telescoping relation, one of said members comprising a tappet body having a chamber adapted to contain a liquid medium through which the thrust of the cam is transmitted to the other member for shifting the valve to open position, spaced inlet and outlet conduits in said supporting body, spaced ports in said tappet body adapted at times to effect communication between said chamber and conduits to permit relative telescoping movement of said members and adapted at other times to be in non-communicating relation to said conduits to permit substantially positive movement of said members in unison.

4. A target mechanism for actuating the valve of an engine, comprising a supporting body, a pair of relatively movable members in said body, one thereof having a chamber adapted to receive a body of liquid through which motion thereof is transmitted to the other member, inlet and outlet conduit means in said supporting body through which said liquid flows into and out of said chamber intermittently to provide relative movement of the members and substantially positive movement thereof in unison sequentially during one valve actuating stroke, and means for varying the volumetric flow of liquid through said conduit means during reciprocation of said chambered member.

5. A tappet mechanism for actuating the valve of an engine, comprising a pair of relatively movable members, one thereof having a chamber adapted to receive a body of liquid through which motion thereof is transmitted to the other member, conduit means through which said liquid flows into and out of said chamber to provide a circulatory path therefor at predetermined times, and inertia means for varying the volumetric fiow of liquid through said conduit means during reciprocation of said chambered member.

6. A hydraulic tappet mechanism for actuating the valve of an engine, comprising a pair of relatively movable members adapted to have a hydraulic medium interposed therebetween in a chamber in one thereof, a support within which the chambered member is reciprocable, in-

let and outlet conduits in said support, and ports in said chambered member adapted to communicate with said conduits to permit relative movement of said members at one time and adapted to reciprocate relative to said conduits during reciprocation of the chambered member to vary said relative movement.

'7. A hydraulic tappet mechanism for actuating the valve of an engine, comprising a pair of rela-' tively movable members adapted to have a hydraulic medium interposed therebetween in a chamber in one thereof, a support within which the chambered member is reciprocable, inlet and outlet conduits in said support, ports in said chambered member adapted, to effect communication between said chamber and conduits to permit relative movement of said members at one time and adapted to reciprocate relative thereto during reciprocation of the chambered member to vary said relative movement, and means for varying the flow of said hydraulic medium through one of said conduits.

8. A hydraulic tappet mechanism for actuating the valve of an engine, comprising a pair of relatively movable members adapted to have a hydraulic medium interposed therebetween in a chamber in one thereof, a support within which the chambered member is reciprocable, inlet and outlet conduits in said support, ports in said chambered member adapted to effect communication between said chamber and conduits and adapted to reciprocate into and out of communication with said conduits during reciprocation of the chambered member, and means for varying the flow of said hydraulic medium through one of said conduits.

14 9. A hydraulic tappet mechanism for actuating the valve of an engine, comprising a pair of relatively movable members adapted to have a hydraulic medium interposed therebetween in a chamber in one thereof, a support within which the chambered member is reciprocable, inlet and outlet conduits in said support, ports in said chambered member adapted to communicate with said conduits to permit relative movement of said members at one time and adapted to reciprocate relative thereto during reciprocation of the chambered member to vary said relative movement, and means responsive to the temperature of said hydraulic medium for varying the flow thereof through one of said conduits.

10. A hydraulic tappet mechanism for actuating the valve of an engine, comprising a pair of v relatively movable members adapted to have a hydraulic medium interposed therebetween in a chamber in one thereof, a support within which the chambered member is reciprocable, inlet and outlet conduits in said support, ports in said chambered member adapted to communicate with said conduits to permit relative movement of said members at one time and adapted to reciprocate relative thereto during reciprocation of the chambered member to vary said relative movement, and thermostatically controlled valve means responsive to the temperature of said hydraulic medium for varying the flow thereof through one of said conduits.

11. A hydraulic tappet mechanism for actuating the valve of an engine, comprising a pair of relatively movable members adapted to have a hydraulic medium interposed therebetween in a chamber in one thereof, a support within which the chambered member is reciprocable, inlet and outlet conduits in said support, ports in said chambered member adapted to communicate with said conduits to permit relative movement of said members at one time and adapted to reciprocate relative thereto during reciprocation of the chambered member to vary said relative movement, and means controlled by the temperature of said hydraulic medium for varying the flow thereof from the inlet conduit through said chambered member and thence through the outlet conduit.

12. A hydraulic tappet mechanism for actuating the valve of an engine, comprising a fixed housing, a pair of relatively movable reciprocable members mounted in said housing, one thereof having a chamber to receive a body of liquid through which motion of such member is transmitted to the other member to open the valve, an inlet conduit in said housing through which liquid is fed to the chambered member, an outlet conduit in said housing spaced from said inlet conduit and through which liquid is dis- 0 charged from the chambered member, and

spaced ports in the chambered member adapted to register with said conduits and through which the liquid intermittently flows from the inlet conduit into said chamber and thence into the 5 outlet conduit during reciprocation of said chambered member.

13. A hydraulic tappet mechanism for actuating the valve of an engine, comprising a fixed support, a pair of relatively movable reciprocable members mounted in said support, one thereof having a. chamber to receive a body of liquid through which motion of such member is transmitted to the other member to open the valve, an inlet conduit in said support through which liquid is fed to the chambered member, an outlet conduit in said support through which liquid is discharged from the chambered member. spaced ports in the chambered member adapted to register with said conduits and through which the liquid intermittently flows from the inlet conduit into said chamber and thence into the outlet conduit during reciprocation of said chambered member, and means for varying the flow of the liquid through one of said conduits.

14. A hydraulic tappet mechanism for actuating the valve of an engine, comprising a Pair of relatively movable reciprocable members, one thereof having a chamber to receive a body of liquid through which motion of such member is transmitted to the other member to open the valve, an inlet conduit through which liquid is fed to the chambered member, an outlet conduit through whichv liquid is discharged from the chambered member, port means in the chambered member through which the liquid intermittently flows from the inlet conduit into said chamber and thence into the outlet conduit during reciprocation of said chambered member, and inertia means for varying the flow of the liquid through one of said conduits.

15. A hydraulic tappet mechanism comprising a support having a, cylindrical bore, a reciprocable tappet body in said bore having a liquid chamber, a plunger associated with said body and adapted to receive the thrust of said tappet body through the column of liquid in said chamber, and spaced conduits in said support opening into said bore and adapted to register with ports in said tappet body for feeding liquid into the chamber and for discharging it therefrom in amounts varying in substantially inverse proportion to the speed of reciprocation of said tappet body.

16. A hydraulic tappet mechanism comprising a support having a cylindrical bore, a reciprocable tappet body in said bore having a liquid chamher, a plunger telescoped with said body and adapted to receive the thrust of said tappet body through the column of liquid in said chamber, and spaced conduits in said support opening into said bore andadapted to intermittently register with ports in said tappet body during the reciprocation of the tappet body for intermittently ining it therefrom.

17. In a hydraulic tappet mechanism for an engine valve,a fixed housing, a reciprocable cam actuated tappet body in said housing, a plunger telescoped in said body and responsive to reciprocation of the body through the medium of a column of liquid within a chamber in said body, and a pair of conduits in said housing spaced apart in fixed relation in the direction of reciprocation of said tappet body for introducing liquid into the chamber and discharging it therefrom in amounts varying substantially in inverse proportion to the speed of reciprocation of said tappet body.

18. In a hydraulic tappet mechanism for an engine valve, a housing, a reciprocable cam actuated tappet body in said housing, a plunger telescoped in said body and responsive to reciprocation of the body through the medium of a column of liquid within a chamber in said body, and a pair of conduits in said housing spaced apart in fixed relation in the direction of reciprocation of said tappet body for introducing liquid into said chamber and for discharging the same therefrom, the amount of liquid so introduced and discharged being controlled by the reciprocation of said tappet body to vary the effective height of said column of liquid and thereby vary the stroke of the plunger with relation to the stroke of the tappet body.

HELMUTH A. MEINECKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,353,993 Fisher Sept. 28, 1920 1,930,260 Almen Oct. 10, 1933 1,936,678 Lampman Nov. 28, 1933 1,965,517 Vitalini July 3, 1934 2,011,864 Lundh Aug. 20, 1935 2,145,484 Johnson Jan. 31, 1939 2,326,883 Pierce et al Aug. 17, 1943 FOREIGN PATENTS Number Country .Date

386,949 Great Britain Apr. 20, 1931 510,864 Great Britain Aug. 9, 1939 

